The code is supposed to Draw several Blue circles and three yellow squares around a logo (the image is a .svg). The generated file shows black circles (instead of blue) and the central logo is absent...
In order to fix it, i wrote two "kod.display()" to see the appearance of the file during the process. The command displays a correct image, with blue circles and the central logo... So it seems that the saving is the root of the problem.

I tried to save in JPG instead of SVG, it works too. So my question is: Why doesn't it want to save the colors and the logo when I generate a .SVG?

I hesitate to respond, since I am new to ImageMagick, but I think the answer is simple.

ImageMagick (and all the wrappers like Magick++) is a *bitmap graphics* package. It allows you to draw vectors, but only in bitmap form -- in other words, once you draw a circle it is converted to a lot of pixel values, and you cannot (directly) get back to the original vector specification. So it is not possible to save in a vector graphics format.

You need an SVG editing package (about which I know nothing, sorry)...